1. Field of the invention
The present invention relates in general to peak detectors, and more specifically to a wide linear range peak detector with increased input range as compared to standard peak detector designs.
2. Description of the related art
Signal level detectors including peak detectors are used in communication systems that use feedback to monitor a signal for purposes of control, such as for controlling an automatic gain control (AGC) circuit or the like. Open-loop systems are known, but are relatively complex and not suitable for many applications. The transfer function of most conventional open-loop configurations is not linear over the entire operating voltage range of the output signal. In order to achieve the desired accuracy, the non-linear portions of the transfer function must be mapped and stored. The greater the non-linearity, the more circuitry or memory required to ensure proper and accurate operation. And such mapping is conducted at the time of manufacture, thereby complicating and slowing down the manufacturing process. Feedback systems are generally more cost effective since open-loop systems require significantly more memory and mapping. The efficiency and effectiveness of a feedback system, however, necessitates the use of a detector that is consistently linear over the necessary range of operation. The present invention is illustrated with detectors for the radio-frequency (RF) signal range, although it is understood that the present invention equally applies to other frequency ranges.
It is desired to extend the linear operating range of a peak detector to improve accuracy and reliability and to simplify a feedback peak detector circuit and the manufacturing process.